Corrugated pallet constructed of folded, interlocked blanks and method

ABSTRACT

An interlock for the top and bottom members of a foldably-constructed pallet and a method of assembling a pallet wherein the top and bottom members are interlocked. By folding straps around the corners of the pallet, either from one sidewall of the pallet around the corner to the adjacent sidewall or from the top of the pallet to the bottom (and optionally from the bottom of the pallet to the top), and anchoring the end of the strap to the adjacent sidewall or the bottom member of the pallet (and if a second strap folded from the bottom member to the top member is utilized, to the top member), the load-bearing capacity of the pallet is substantially increased.

This application claims the benefit of U.S. Provisional Application Nos. 61/664,827, filed Jun. 27, 2012, and 61/665,358, filed Jun. 28, 2012, which related applications are hereby incorporated in their entirety into this application by this specific reference thereto. This application is also a continuation-in-part of co-pending application Ser. No. 13/134,092, filed May 27, 2011, and a continuation-in-part of co-pending application Ser. No. 13/134,508, filed Jun. 9, 2012, and both prior co-pending applications are also hereby incorporated into this application in their entirety by this specific reference thereto.

The present invention relates generally to a force-resisting structure or support and, more particularly, to a force-resisting structure or support foldably constructed from one or more foldable blanks and especially suited for use as a pallet or dunnage support. In more detail, this invention pertains to pallets for shipping goods, and more particularly to a corrugated paperboard pallet that provides strong and stiff load support utilizing fully recyclable corrugated, and a method of assembling a corrugated paperboard pallet for use in shipping goods that reduces direct and indirect shipping costs. The pallet of the present invention reduces costs by utilizing only two flat paperboard blanks and by requiring the minimum amount of material while being completely machine-assembleable on-site at a shipping facility for rapid, high volume use. The assembly method of the present invention reduces waster material and facilitates just-in-time palletizing with minimal labor, storage, transport, and uncertainty costs.

A pallet is primarily used to accommodate the mechanized bulk handling and transport of products. A pallet typically comprises a flat top surface for supporting a load, such as goods, containers, or packages, a sufficient distance above the ground or floor so that the fork of a forklift can be inserted under the top surface in order to move the pallet with the entire load thereon from place to place. Traditionally, most pallets have been made from pieces of wood, specifically soft wood, assembled with metal fasteners such as nails or screws. However, a number of problems face present day users of conventional wooden pallets. The rising cost of making and repairing wooden pallets has detracted from the overall cost effectiveness of palletized shipments. Wooden pallets are heavy, bulky and cumbersome, and empty wooden pallets require substantial storage space. It is especially costly to transport empty wooden pallets by rail or truck for reuse.

To save costs, conventional wooden pallets are returned to the shipper for reuse, but since wooden pallets are heavy, bulky and cumbersome, they are inconvenient to store and relatively expensive to return to the shipper. If the wooden pallet is not reused, it must be disposed of in a proper manner. Generally speaking, landfill or other waste disposal sites will not accept wooden pallets as is; rather, the pallets must first be reduced either by chipping or burning prior to disposal. Chipping adds significant cost to wooden pallet disposal, and burning wooden pallets is often precluded by environmental regulations.

Some used wooden pallets are retrieved by pallet recyclers, who usually accept only certain sizes of wooden pallets and commonly charge a fee for their retrieval. After repair or refurbishment, the recycler may attempt to resell the used wooden pallets. The market for recycled wooden pallets is limited, however, because many retailers refuse to receive goods transported on recycled wooden pallets due to the lack of any standards regulating the quality of the repair or refurbishment of used wooden pallets. Products shipped internationally on even new wooden pallets are faced with increasing regulations requiring various forms of chemical treatment to the wood to prevent infestation and transport of insects and parasites. Pallets constructed of plastic or metal have been proposed, but plastic and metal pallets have many of the same disadvantages as wooden pallets including being heavy, bulky and cumbersome, being costly and inconvenient to transport, store and dispose of, and being incompatible with environmental preservation. In view of the various drawbacks to pallets made from wood, plastic or metal, it would be desirable to construct a pallet from a material other than wood, plastic or metal, while maintaining many of the desirable characteristics generally associated with pallets made from wood, plastic and metal to provide a pallet that is lighter in weight, less expensive, strong, of simplified construction, easier and less costly to transport and store, that requires less space for storage, that is more readily recyclable or disposable, and that minimizes environmental impact.

Pallets made of corrugated paperboard have been proposed, including pallets constructed from foldable corrugated paperboard blanks as represented by U.S. Pat. No. 6,029,582 to Ogilvie, Jr. et al. In many conventional corrugated paperboard pallets, the vertical supports for the elevated top surface of the pallet are secured with extraneous fasteners, including adhesive fasteners such as glue or mechanical fasteners such as staples or clips, and are not secured by the paperboard blanks themselves. Since an individual pallet ordinarily includes a plurality of vertical supports, the need to apply an extraneous fastener to each vertical support adds to the cost, time, labor and complexity involved in constructing or assembling the pallet. Furthermore, paperboard pallets in which the vertical supports are secured with extraneous fasteners are usually lacking in torsional strength. The extraneous fasteners also introduce undesirable materials into the pallet, and the fasteners may limit or complicate recyclability of the pallet. Some paperboard pallets rely on frictional securement of a top member of the pallet, which defines the elevated top surface, to a bottom member of the pallet, and such frictional securements lend little or no torsional support or strength to the overall pallet structure. Many conventional paperboard pallets do not have full perimeter support for the elevated top surface. Consequently, the force from a load carried on the elevated top surface can cause the elevated top surface to deflect in areas where the load is not directly supported by vertical supports of the pallet. Some conventional paperboard pallets cannot be foldably constructed or assembled from a single paperboard blank but, rather, require at least two foldable paperboard blanks that are assembled and then fastened together with extraneous fasteners. Some paperboard pallets attempt to duplicate the design of conventional wooden pallets, and these pallets are usually both heavy and expensive despite being made of paperboard.

For the many reasons of reducing costs, increasing recyclability, lowering pallet weight, eliminating product contamination, and reducing injuries, there is a desire to replace conventional wooden pallets with corrugated pallets. There is also a desire to have corrugated pallets that can be shipped flat and then be completely machine- assembled on-site at a product shipper to facilitate high volume, just-in-time supply and to reduce pallet storage space and costs. To date, corrugated pallets have required some or total hand assembly, making high volume use difficult, have used excessive amounts of corrugated paperboard, making them expensive, and have had less than sufficient strength and stiffness for shipping many loads. Accordingly, an improved corrugated pallet is needed that provides increased strength and stiffness for widespread use in shipping, that makes minimal use of corrugated for lower costs, and that can be completely machine-assembled for rapid, high-volume product shipping applications.

Various objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings wherein like reference numerals refer to like or similar parts. Those skilled in the art will recognize, however, that the embodiment(s) of the present invention that are described and shown herein are only examples of specific embodiment(s), set out for the purpose of describing the making and using of the present invention, and that the embodiment(s) shown and/or described herein are not the only embodiment(s) of a method and apparatus constructed and/or performed in accordance with the teachings of the present invention.

The present invention is an apparatus for assembling the top and bottom blanks of a foldably-constructed pallet in nested relation comprising an intake for taking up and registering a top blank, an intake for taking up and registering a bottom blank, clamps for folding the registered top and bottom blanks to form support ribs therein; a joiner for compressing the folded top and bottom blanks to each other in nested relation to form the pallet; and a mandrel for folding a strap formed on either of the top or bottom blank into contact with the opposite blank and for inserting the end of the strap into a cut formed in the material comprising the opposite blank for interlocking the top and bottom blanks.

The present invention is also a method for interlocking top and bottom substantially planar members in nested relation comprising the steps of folding a flap formed on a substantially planar top member to a position substantially perpendicular to the planar surface of the top member and folding a flap formed on a substantially planar bottom member to a position substantially perpendicular to the planar surface of the bottom member, the flap on the top member forming a sidewall and the flap on the bottom member forming an end wall when the top and bottom members are in nested relation. A strap extending from either the flap forming the sidewall or the flap forming an end wall is then folded around the corner formed by the end wall and sidewall and the end of the strap is inserted into a slot formed in the other of the sidewall or the end wall and the end of the strap is retained in the slot.

In another aspect, a method of resisting torsional force exerted on a force resisting structure comprised of top and bottom substantially planar members, either or both of the top and bottom planar members having folded portions forming sidewalls when and assembled to each other in nested relation, comprising the steps of folding a strap formed integrally with the top member into contact with the bottom member and inserting a tab formed on the end of the strap into a cut formed on the bottom member. A tab formed on the end of the strap is then retained in the cut.

Referring to the figures,

FIG. 1 is a perspective view of a first embodiment of a foldably-constructed, force-resisting corrugated paperboard pallet that is constructed in accordance with the present invention.

FIG. 2 is a perspective view of the first, or top, and second, bottom member of the foldably constructed force-resisting structure of FIG. 1 prior to being foldably constructed into a corrugated paperboard pallet in accordance with the method of the present invention. FIG. 3 is a perspective view of the top surface of the second, bottom member of the pallet of FIG. 1 prior to assembly in accordance with the present invention.

FIG. 4 is a perspective view of the underside of the first, top member of the foldably-constructed force-resisting corrugated paperboard pallet of FIG. 1 prior to assembly in the assembly method of the present invention.

FIG. 5 is a perspective view of the pallet bottom and pallet top of the pallet of FIG. 1 aligned prior to compression together in accordance with the assembly method of the present invention.

FIG. 6 is a perspective view of the pallet bottom and pallet top of the pallet of FIG. 1 after being compressed together in accordance with the assembly method of the present invention.

FIG. 7 is a perspective view of the pallet of FIG. 1 after the tuck flaps have been inserted into the corresponding cuts, or slots, in accordance with the assembly method of the present invention.

FIG. 8 is a perspective view of the pallet of FIG. 1 after the jack passages are folded open in accordance with the assembly method of the present invention.

FIG. 9 is a perspective, detailed view of one of the corners of the foldably-constructed, force-resisting corrugated paperboard pallet of FIG. 1 before a strap formed integrally with the sidewall of the bottom member and comprising an interlocking element constructed in accordance with the present invention is folded over and inserted into a cut formed in the top member for retention therein.

FIG. 10 is a perspective, detailed view similar to FIG. 10 showing the strap folded into contact with the top member.

FIG. 11 is a perspective, detailed view similar to FIG. 10 showing the strap after insertion of the tab formed on the end of the strap into the cut formed in the top member.

FIG. 12 is a partial sectional view taken along the lines 12-12 in FIG. 1 showing the manner in which the tabs formed on the end of the straps interact with the cut formed in the top and bottom members.

FIG. 13 is a partial sectional view taken along the lines 13-13 in FIG. 1 showing the manner in which the tab formed on the end of the strap integral with the sidewall of the bottom member interacts with the margin of the cut formed in the top member.

FIG. 14 is a perspective view of the underside of the force-resisting structure of FIG. 1.

FIG. 15 is a broken, perspective view of a second embodiment of an interlocking arrangement for the peripheral side walls of the force-resisting structure of the present invention.

FIGS. 16A-16D are perspective views similar to the views shown in FIGS. 9-14 of the interlocking arrangement for the peripheral side walls showing the steps of assembling the interlock.

FIGS. 17A-17F are broken, perspective views of a third embodiment of the interlocking arrangement for the peripheral side walls of a force-resisting structure of the present invention showing the steps of assembling the interlock.

FIG. 18 is a schematic diagram of a corrugated paperboard pallet assembly machine for assembling corrugated pallets in accordance with the method of the present invention.

FIG. 19 is a schematic diagram of a machine process for use with the corrugated paperboard pallet assembly machine of FIG. 18.

Turning to the drawings, wherein like reference numerals designate identical or corresponding parts, FIG. 1 shows a corrugated paperboard pallet 30 in accordance with the present invention. The pallet 30 has two sets of jack passages 31, 32 for lifting and moving the pallet when loaded and is comprised of a pallet bottom 50 and pallet top 70. The pallet of FIG. 1 prior to assembly in flat blanks state is shown in FIG. 2 and is constructed from the two flat sheets that form the pallet bottom 50 and pallet top 70. Preferably, the sheet material from which blanks 50 and 70 are made is paperboard and, most preferably, corrugated paperboard. However, thermal plastics or ductile metals could be used for the sheet material. The blanks 50 and 70 can each be cut in any suitable manner from the sheet material, such as by die or stamp cutting, and can be treated in various ways to make them suitably moisture and water resistant. Blanks 50 and 70 can be made from virgin materials or from recycled materials and if made of paperboard sheet material, are easily and routinely recyclable while maintaining many of the desirable characteristics of less readily recyclable materials such as wood, metal and various plastics.

As explained further below, each blank 50, 70 has foldable portions foldable along fold or crease lines defined or formed in the blanks in order to foldably construct or assemble the top and bottom members. Each blank 50, 70 is provided, where necessary, with cut lines creating separable edges in the blanks for various purposes including to define or form the foldable portions and/or other structural elements, and/or to allow for or facilitate folding of the foldable portions. The cut lines can be formed as complete cuts extending entirely through the thickness of the sheet material to form completely severed separable edges. Alternatively, the cut lines can be formed as partial cuts, such as perforations or score lines, extending partly through the thickness of the sheet material comprising blanks 50, 70 to form partly severed, separable edges that can be severed completely during foldable construction or assembly. Either or both blanks 50, 70 may be provided with one or more cut-out windows of various shapes and sizes where the sheet material is partially removed or is completely removed during foldable construction or assembly to serve various purposes. Some of the purposes that may be served by the provision of cut-out windows include simplifying the manufacture or preparation of the blanks, facilitating foldable construction or assembly of the force-resisting structure, allowing for interlocking engagement between portions of the same or different blanks, and reducing weight when possible without sacrificing structural strength. The peripheral dimensions and thickness of the blanks 50, 70 and the location of the fold lines, cut lines and cut-out windows can vary in accordance with the features desired for the force-resisting structure 30 based on its intended application.

The pallet bottom 50 of pallet 30 is shown in the assembly process with ribs folded up in FIG. 3. The pallet bottom 50 is folded in the manner described in the above-incorporated U.S. application Ser. No. 13/134,092 to produce two parallel rib sets 51 near the midsection. Briefly, the parallel rib sets 51 comprise edge ribs 52 located at each edge of the pallet bottom 50 having horizontal notches 53 and middle ribs 54 located in the middle of the pallet bottom having vertical notches 55. The pallet bottom 50 also comprises punch locks 56 in the parallel rib sets 51 for locking them in place once folded. To allow for wheels of a pallet jack to lift the pallet 30, cutouts 57 are provided in the pallet bottom 50. Although as described above, other materials may be used, in the embodiment shown, the pallet bottom 50 is constructed of double wall B-C flute corrugated having a cross direction 90 and machine direction 91 and the cross direction 90 is aligned such that it becomes the vertical direction in the parallel rib sets 51 for high pallet strength and stiffness.

The pallet top 70 of pallet 30 is shown in the assembly process with ribs folded down in FIG. 4. The pallet top 70 is folded to produce two parallel rib sets 71 near the midsection, also in the manner described in the above-incorporated U.S. application Ser. No. 13/134,092. The parallel rib sets 71 comprise edge ribs 72 located at each edge of the pallet top 70 having horizontal notches 73 and middle ribs 74 located in the middle of the pallet top having vertical notches 75. The pallet top 70 also comprises punch locks 76 in the parallel rib sets 71 for locking them in place once folded. The pallet top 70 is constructed of double wall B-C flute corrugated having a cross direction 100 and machine direction 101 and the cross direction 100 is aligned such that it becomes the vertical direction in the parallel rib sets 71 for high pallet strength and stiffness.

After the rib sets 51, 71 re formed in both the pallet bottom 50 and pallet top 70, the top and bottom 50, 70 are brought together and aligned as shown in FIG. 5 (the process of aligning the pallet top and bottom 50, 70 is described in more detail below). The pallet bottom 50 is aligned perpendicular to the pallet top 70 such that the rib sets 51, 71 intersect and such that the vertical notches 55, 75 of the middle ribs 54, 74 are positioned vertically intercepting each other as described in U.S. Ser. No. 13/134,092. The pallet is then assembled by compressing the pallet bottom 50 and pallet top 70 together as shown in FIG. 6. The top of the rib sets 51 of pallet bottom 50 rest on the underside of pallet top 70 and the bottom of rib sets 71 of pallet top 70 rest on the top side of pallet bottom 50.

After assembling the rib sets 51, 71 of the pallet bottom 50 and pallet top 70 together, the outer edge of the pallet 30 is assembled. The assembly steps are set out in detail in Ser. No. 13/134092 and briefly shown in FIGS. 7-8, FIG. 7 showing insertion of the tuck flaps. The outer edges of the pallet 30 are formed by inserting bottom tuck flaps 80 into the edge notches 73 of pallet top 70 and by inserting top tuck flaps 81 into the edge notches 53 of the pallet bottom 50. The corners of the pallet bottom 50 form bottom locking straps 82 and the corners of the pallet top 70 form top locking straps 83, both as described in more detail below. To permit lifting of the pallet 30, passages for the forks of a pallet jack (not shown) are opened as shown in FIG. 8. The folding of the bottom tuck flaps 80 and top tuck flaps 81 creates pallet outer sidewalls 86, 87. The outer sidewalls 86, 87 comprise flaps 84, 85 that are folded inwardly on each side of pallet 30 to create jack passages 31, 32.

The pallet bottom 50 and pallet top 70 are then locked together to provide a strong and reliable load carrying capability with the completed pallet 30 as shown in FIG. 9. The interlocking arrangement for the peripheral side walls of the force-resisting structure constructed as shown in FIG. 1 is assembled by folding bottom locking straps 82 over the top surface of pallet top 70 and folding the top locking straps 83 under the bottom surface of pallet bottom 40. After folding the straps 82, 83, the tabs 166 formed on the ends of straps 82, 83 are each inserted into respective cuts 161, 261 in the pallet top 70 and pallet bottom 50 as shown in FIG. 1 to complete the locking and finish assembling pallet 30.

To assemble the interlock, and as shown in more detail in FIGS. 9-14, the ends of the locking straps 82, 83, which are initially in the upright, or unfolded, position extending perpendicularly to the flat surface of the top and bottom members 50, 70 as shown in FIGS. 7, 8, and 9, are folded into contact with the flat surface of the corresponding top and bottom members 50, 70. In the next step in the method of assembling the interlock, the tab 166 formed on the ends of the respective straps 82, 83 is inserted into the corresponding cut 161, 261.

As best shown in FIG. 9, the cuts 161, 261, are formed in the shape of a “C” with the closed side of the “C” closest to the corner formed by the pallet sidewalls 86, 87. Referring to FIGS. 11 and 12, it can be seen that when the tab 166 on the end of the respective strap 82, 83 is inserted into the cut 161, 261, a portion of the material comprising the top and bottom members 50, 70 in which the cut 161, 261 is located is deflected downwardly, or inwardly, forming a retaining tab 174. Retaining tab 174 bears against the tab 166 to resist movement of the tab 166 in the direction of the arrow 176 shown on FIG. 13 that would allow tab 166 to pull out of cut 161, 261, thereby effectively locking tab 166 in cut 161, 261. Note also that after tab 174 has been inserted through the cut 161, 261, any attempt to pull tab 166 back out of the cut 161, 261 causes the surfaces 180 formed by the notches 178 in the material comprising locking strap 82, 83 to engage the edges of cut 161, 261, the surfaces 180 acting as stops to resist movement of the tab 174 back out of cut 161, 261. As shown in FIGS. 8 and 9, both the top and bottom members 50, 70 of pallet 30 are provided with straps 82, 83. As a result, and as best shown in FIG. 14, each of the corners formed by the sidewalls 86, 87 is “wrapped” by straps 82, 83 that extend from the bottom member 70 up over top member 50 and from top member 50 down under bottom member 70 on the two sides formed by the sidewalls 86, 87 of each corner to provide effective resistance to torsional forces on pallet 30, thereby effectively increasing the load bearing capacity of pallet 30.

FIG. 15 illustrates a second embodiment of the locking arrangement by which overlapping side walls of the top and bottom members are interlocked. The locking arrangement is depicted in FIG. 15 in conjunction with the overlapping side wall segments 937, 1037 at corners of the top member 912 and bottom member 913 as they are assembled in nested relation to form the force-resisting structure 910. The side wall segment 937A which meets or is adjacent another side wall segment 937B at a corner of the top member 912 is provided with a locking slot 961. The corresponding side wall segment 1037A of bottom member 913 which meets or is adjacent another side wall segment 1037B at a corner of bottom member 913 is provided with a locking slot 1061 which is aligned with the locking slot 961 when the top member 912 is assembled in nested relation over the bottom member 913. A locking strap 963 formed from the top member blank and foldably connected to the end of side wall segment 937B is folded around the corner of the peripheral side wall of top member 912 and a locking tab 966 on strap 963 is inserted into the aligned locking slots 961 and 1061.

As noted above, the interlocking arrangement of the present invention is, in one embodiment, designed for automated assembly, and the assembly steps are set out in sequence in FIGS. 16A-16B. FIG. 16A is similar to FIG. 9 in that FIG. 16A shows the strap 82 extending from bottom member 50 after the top and bottom members 50, 70 have been assembled to each other as shown in FIG. 8, at which point an “L”-shaped mandrel 168 is aligned with each of the corners formed by sidewalls 86, 87 (only one corner being shown in FIG. 16 for purposes of clarity). Mandrel 168 is then pivoted in the direction of arrow B in FIG. 16A to the position shown in FIG. 16B, the “L”-shape of mandrel 168 causing the strap 82 to be folded into contact with the top surface of top member 70. The pneumatic cylinder 169 mounted to mandrel 168 is then activated (see below) to extend piston 171 in the direction of arrow C as shown in FIG. 16C to punch, or insert, the tab 174 of strap 82 into the “C”-shaped knife cut 161 in top member 70. As described above, the “C”-shaped cut causes the material comprising top member 70 to deflect downwardly along with the tab 166 on the distal end of strap 82 to form the retainer tab 174 upon withdrawal of the piston 171 as shown in FIG. 16D. The end of piston 171 is provided with a ball 173, the rounded surfaces of ball 173 facilitating insertion and withdrawal from the cut 161 to punch the locking tab 166 and retainer tab 174 through knife cut 161 and to leave the tabs 166, 174 in the cut 161 upon withdrawal of the ball 173.

A third embodiment of the locking arrangement, or corner lock, is shown in FIG. 17, and like the embodiment shown in FIGS. 1-14, because the embodiment shown in FIG. 17 is adapted for automated assembly of a force resisting structure constructed in accordance with the method of the present invention, FIG. 17 appears as a series of steps FIG. 17A-17F for automated assembly of the locking arrangement. Referring first to FIG. 17A, top member 1112 and bottom member 1113 are shown in nested relation, each of top and bottom members 1112, 1113 being provided with flaps folded substantially perpendicularly to form respective sidewalls 1136 and 1137 including side wall segments 1136A and 1137A that meet at a corner of the respective top and bottom members 1112, 1113. To provide increased resistance to torsional forces, a locking strap 1163 formed from the top member blank and foldably connected to the end of side wall segment 1137B is folded around the corner of the peripheral side wall of top member 1112 (FIG. 17B) and a locking formation, or tab, 1166 on strap 1163 is inserted into the locking slot 1161 as shown in FIG. 17F by action of the mandrel 1168 of a device (not shown) for automated assembly of force resisting structure 1110. Both top and bottom members 1112, 1113 are provided with locking slots and the respective locking slots are aligned when the top and bottom members are assembled to each other in nested relation for insertion of the tab 1166 on strap 1163, but only the locking slot 1161 formed in top member 1112 is visible in FIG. 17.

As best shown in FIG. 17C, mandrel 1168 engages the outside surface of locking strap 1163 as it moves in the direction indicated by the arrow in FIG. 17C to drive the locking tab 1166 on the end of strap 1163 through locking slot 1161 as shown in FIGS. 17D and 17E. The mandrel 1168 then reverses direction, leaving locking tab 1166 in slot 1161 as it retreats.

As best shown in FIG. 17A, a knife cut 1170 through the material comprising side wall segment 1136A of top member 1112 extends from one side of locking slot 1161, allowing the corners 1172 of the material comprising the side wall segment 1136A of top member 1112 to deflect inwardly (in other words, to deflect in the same direction as the arrow in FIG. 17C showing the direction of movement of mandrel 1168) to facilitate insertion of tab 1166 through locking slot 1161 (for this reason, corners 1172 are also referred to herein as flaps 1172). Those skilled in the art who have the benefit of this disclosure will recognize that knife cut 1170 is not required for insertion of locking tab 1166 through locking slot 1161, but being located at a point on wall segment 1136A that is aligned with mandrel 1168 when mandrel 1168 engages locking strap 1163, the knife cut 1170 facilitates insertion of tab 1166 through locking slot 1161 for automated assembly of top and bottom members 1112, 1113. Although the knife cut 1170 is shown in FIG. 17 as extending from locking slot 1161 in a direction approximately perpendicular to the long dimension of locking slot 1161 in the embodiment shown in FIG. 17, those skilled in the art will recognize that knife cut 1170 need not be perpendicular to the long dimension of locking slot 1161; the corners 1172 at the intersection of locking slot 1161 and knife cut 1170 function as flaps that deflect inwardly in the manner described herein even if knife cut 1170 extends at an angle from locking slot 1161. It will also be apparent from a review of the preferred embodiment shown in FIG. 17 that locking slot 1161 is provided with knife cuts 1171 that extend in a direction parallel to the long dimension of the locking slot. Although not required for the corner lock of the present invention to function for its intended purpose of interlocking the top and bottom members of a force resisting structure as described herein, the parallel knife cuts 1171 do cooperate with perpendicular knife cut 1170 and the mandrel 1168 that engages locking strap 1163 to facilitate passage of the locking formation 1166 through locking slot 1161 for automated assembly of the corner lock of the present invention as described herein. Note also that, just as knife cut 1170 need not extend from locking slot 1161 in a direction that is perpendicular to the long dimension of locking slot 1161, it is not required that the knife cut 1171 extend in a direction that is parallel to the long dimension of locking slot 1161; the knife cut 1171 functions in the manner described herein even if knife cuts 1171 extend at an angle from locking slot 1161 and/or if only one end of locking slot 1161 is provided with a knife cut 1171.

It will be appreciated that, although described herein as being located in the wall segment 1136A of the side wall 1136 of top member 1112, wall segment 1137A of the side wall 1137 of bottom member 1113 is likewise provided with a locking slot, knife cut(s), and beveled flaps. However, because the structure in wall segment 1137A is not visible in the perspective view shown in FIG. 17 (because of the alignment of the respective slots, knife cuts, and flaps), the description set out herein refers to wall segment 1136A. To further facilitate automated assembly of top member 1112 to bottom member 1113, the corners 1172 at the intersection of locking slot 1161 and knife cut 1170 are angled, or beveled, by relief cuts 1174. As a result of the beveled relief cuts 1174 of flaps 1172 and the deflection of the flaps 1172 by mandrel 1168, a hole 1176 is formed in the material comprising wall segment 1136A and, as best shown in FIG. 17E, after driving tab 1166 through locking slot 1161, mandrel 1168 extends through and is subsequently withdrawn from that hole 1176.

The notches 1178 located near the distal end of locking strap 1163 define the above-described locking formation 1166 and serve at least two functions. First, notches 1178 are aligned with the point at which mandrel 1168 engages the outside surface of locking strap 1163, as well as the opening to locking slot 1161, to provide a point of weakness along which the material comprising locking strap 1163 deforms as the portion of locking strap 1163 comprised of locking formation 1166 is driven through the locking slot 1161 past the deflecting flaps 1172, thereby allowing the locking formation 1166 to be inserted through locking slot 1161. Second, after locking formation 1166 has been driven through locking slot 1161, top and bottom members 1112, 1113 are interlocked in the sense that any attempt to pull locking formation 1166 back out of locking slot 1161 causes the surfaces 1180 formed by the notches 1178 in the material comprising locking strap 1163 to engage the edges of locking slot 1161, the surfaces 1180 acting as stops to resist movement of the locking formation 1166 back out of locking slot 1163. As noted above, knife cuts 1171 are not considered essential to the function of the interlocking fastening element of the present invention, but if those cuts 1171 are utilized, they provide an additional advantage such that the preferred embodiment of the invention includes the cuts 1171. Specifically, when a force is exerted on either the top or bottom member 1112, 1113 that causes the two members to tend to separate from each other such that locking formation 1166 is pulled in a direction out of locking slot 1161, the stop surfaces 1180 engage the back side of the material comprising the wall segments 1136 and/or 1137 near the knife cuts 1171. As a result of the engagement of the stop surfaces 1180 and the material comprising the wall segments 1136, 1137 near knife cuts 1171, the material comprising wall segments 1136, 1137 deflects outwardly at knife cuts 1171, thereby reducing the tendency of stop surfaces 1180 to wear and/or deform. Over repeated cycles of the pulling of locking formation 1166 out of locking slot 1161, the deflection of the material comprising wall segments 1136, 1137 at knife cuts 1171 substantially reduces the likelihood that the corners of stop surfaces 1180 will be worn, deformed, or even sheared off, to the point that they do not function to resist movement of locking formation 1166 back out of locking slot 1163.

It should be appreciated that the locking arrangement can be used to interlock various overlapping side walls of the top and bottom members at the corners or at other locations along the side walls (the interlocking fastening element of the present invention is referred to herein as a “corner lock” only because it is located at the corner of the preferred embodiment of a force resisting structure, not because it must be located at a corner). It should also be appreciated by those skilled in the art who have the benefit of this disclosure that the insertion of a tab 166 (FIGS. 9-14) or locking formation 1166

(FIGS. 15 and 17) located on the end of a locking strap into locking slot is but one way to provide resistance to torsional force at the corners of the foldably-constructed force-resisting member of the present invention. The same desirable resistance to torsional (and other) forces can also be provided by a mechanical fastener, such as stapling, at the corners of force resisting structure 910, 1110, or by gluing or in other ways known in the art. In another embodiment (not shown), a locking strap similar in structure to strap 1163 located on a top or bottom member is not provided with a locking formation; instead, the distal end of the locking strap is passed through a locking slot and then secured to the respective side wall segment of the other of the top or bottom member by a mechanical fastener such as by stapling, gluing, or other ways as known in the art. This alternative embodiment retains an advantage of the force-resisting structures of the present invention in that the top and bottom members are interlocked in nested, assembled relation due to the interlocking relationship between portions of the top and bottom members, i.e. the initial blanks themselves.

Structural strength, rigidity and integrity, including increased torsional strength and load support strength, are enhanced because the portions of the top and bottom members that interlock, secure or are secured to other portions, and/or provide vertical support for the top member base panel, are formed from the initial blanks of sheet material and remain integral with the blanks. Structural strength, rigidity and integrity, including torsional strength and load support strength, are also enhanced due to the snug fit of the wings, the side wall flaps and/or the vertical support ribs in the interior of the force-resisting structures. The vertical support ribs form “X”-shaped or cross-shaped vertical support structures within the force-resisting structures for enhanced load support strength. The “X”-shaped or cross-shaped vertical support structures are formed by interlocking top and bottom support ribs or by support ribs provided in either the top or bottom member. The force-resisting structures are designed so that loads are supported along the lines of corrugation of the sheet material for greater strength, rigidity and integrity, including greater torsional strength and load support strength. The side wall flaps and/or the wings are arranged to provide vertical support entirely around the perimeter of the force-resisting structures to resist deflection of the top member base panel. The side portions of the top and bottom members include side walls, with or without tuck flaps, and/or retention elements and the side walls are either continuous or formed as side wall segments separated by spaces. The side walls of the bottom members fit interiorly of side walls of the top members when the top and bottom members are in nested relation. Alternatively, the side walls of the top members fit interiorly of the side walls of the bottom members in nested relation. The side walls of the top and bottom members are secured in overlapping relation and a locking arrangement formed from the initial blank is used to secure overlapping side walls, especially at the corners of the force-resisting structures. The top and bottom members are easily manufactured and shipped and/or stored in the unfolded condition in which the top and bottom members occupy minimal space due to their flat or planar configuration. The force-resisting structures are disassembled or broken down for return to the unfolded condition subsequent to use and are readily and easily recyclable or disposable. Accordingly, the force-resisting structures minimize adverse environmental impact, occupy minimal space prior to and/or subsequent to assembly, and effectively save in production, storage and transportation costs.

Referring now to FIG. 18, a schematic diagram of a corrugated paperboard pallet assembly machine for use in assembling the pallet 30 of FIG. 1 is shown. The pallet assembly machine 550 takes in top blanks 561 into a pallet top former 552 and takes in bottom blanks 553 into the pallet bottom former 554. The top and bottom joiner 555 assembles and folds together the pallet tops and pallet bottoms to form finished pallets 556. The pallet assembly machine 550 is operated by a control 557 that comprises a controller 568 and solenoid valves 569. A compressor 560 feeds air to the control 557 that operates the pallet top former 552, pallet bottom former 554 and pallet top and bottom joiner 555. In one embodiment, the pallet assembly machine 550 comprises open loop pneumatic control for reliability and low costs. In the pallet top former 552 is the initial step of registration 561 to insure proper location and operation on the top blanks 551. In the pallet bottom former 554 is the initial step of registration 563 to insure proper location and operation on the pallet bottom blanks 553. In the top and bottom joiner 555, the initial step is also registration 562.

A schematic diagram of a machine process for use with a corrugated paperboard pallet production machine of FIG. 18 is shown in FIG. 19. The process comprises three sections, the pallet top former 580, pallet bottom former 581 and pallet top and bottom joiner 582. The three sections 580, 581, 582 work together to form a completed pallet. The pallet top former 580 comprises the steps of picking up the top blank 583, taking in the top blank 584, registering the location of the top blank 585, stopping motion of the corrugated blank 586, clamping the top blank 587 and folding the vertically extending members 588 on the top blank The pallet bottom former comprises the steps of picking up the bottom blank 589, taking in the bottom blank 590, registering the location of the bottom blank 581, stopping motion of the corrugated blank 592, clamping the bottom blank 593 and folding the vertically extending members 594 on the bottom blank The pallet top and bottom joiner comprises the steps of taking in the pallet top and bottom 595, registering the location of the pallet top and bottom 596, stopping the motion of the corrugated pallet top and bottom 597, clamping the pallet top and bottom together 598, and folding the pallet top and bottom together 599. Pneumatic cylinders (see, for instance, FIG. 16) are then activated at the command of controller 568 to fold the flaps 84, 85 to create jack passages 32 at step 599A.

At step 599A, the top and bottom members 50, 70 appear as shown in FIG. 8 and in the next two steps 599B and 599C, controller 568 activates another set of pneumatic cylinders to fold straps 82, 83 into contact with the respective top and bottom members 50, 70 as shown in FIG. 16 and then to insert the tabs 166 on the ends of the straps into the respective cuts 161, 261 on top and bottom members 50, 70. Folding of straps 82, 83 and insertion of the tabs 166 into cuts 161, 261 is accomplished by the “L”-shaped mandrel 168 (FIG. 16) in the directions of arrows B and C as shown in FIG. 16. After locking the tabs 166 in the respective cuts 161, 261, the cycle is completed by ejecting the completed pallet to a palletizer as at step 600. Of course those skilled in the art will recognize that if the pallet assembly machine is being used to assemble a pallet having an interlocking member as shown in FIG. 17, the tab 1166 is inserted into the knife cut, or slot 1170 by movement of the mandrel 1168 in just a single direction (as shown by the arrow in FIG. 17C) by activation of a pneumatic cylinder without pivoting. After each pallet 30 is ejected, the pallet assembly machine repeats the cycle 601 upon receipt of a signal from the palletizer that another pallet is needed.

Those skilled in the art who have the benefit of this disclosure will also recognize that certain changes can be made to the component parts of the apparatus of the present invention without changing the manner in which those parts function and/or interact to achieve their intended result. For example, rather than using the “L”-shaped mandrel 168 (FIG. 16) to fold the straps 82, 83 around the corners and into contact with the respective top and bottom members 50, 70, the straps can be scored to form a point of weakness that results in folds at the desired locations simply by striking the back side of the straps with separate mandrels moving in the directions of arrows B and C in FIG. 16. Similarly, it will be recognized that the structure shown in FIG. 15 can be adapted for automated assembly by, for instance, using an “L”-shaped mandrel that pivots around the corner formed by sidewalls 937, 1037 with a pneumatic cylinder mounted thereto that drives the locking formation, or tab, 966 on the end of strap 963 into the aligned slots 961, 1061. All such changes, and the many others that will be clear to those skilled in the art from this description of these several embodiment(s) of the invention, are intended to fall within the scope of the following, non-limiting claims. 

What is claimed is:
 1. A method of resisting torsional force exerted on a force resisting structure comprised of top and bottom substantially planar members, either or both of the top and bottom planar members having folded portions forming sidewalls when and assembled to each other in nested relation, comprising the steps of: folding a strap formed integrally with the bottom member into contact with the top member; inserting a tab formed on the end of the strap into a cut formed on the top member; and retaining the tab formed on the end of the strap in the cut.
 2. The method of claim 1 wherein a strap formed integrally with the top member is folded into contact with the bottom member for inserting a tab formed on the end of the strap into and retaining within a cut formed on the bottom member.
 3. The method of claim 1 wherein the tab formed on the end of the strap is driven through the cut by a mandrel that engages the strap.
 4. The method of claim 1 wherein the tab formed on the end of the strap is retained in the cut by a mechanical fastener.
 5. The method of claim 1 wherein the tab formed on the end of the strap is retained in the cut by contact between the tab and the material comprising the top member that is deflected by insertion of the tab into the cut.
 6. The method of claim 1 wherein the tab is retained in the cut by engagement of the material comprising the top member by notches formed in the strap.
 7. The method of claim 1 wherein the strap is folded into contact with the top side of the top member.
 8. The method of claim 7 wherein the cut formed on the top member is formed on the top side of the top member.
 9. The method of claim 1 additionally comprising the steps of: folding a strap formed integrally with the top member into contact with the bottom member; inserting a tab formed on the end of the top member strap into a cut formed on the bottom member; and retaining the tab formed on the end of the top member strap in the cut formed in the bottom member.
 10. The method of claim 10 wherein the strap formed integrally with the top member is folded into contact with the bottom member on one side of the corner formed by the sidewalls of the top and bottom members and the strap formed integrally with the bottom member is folded into contact with the top member on the other side of the corner formed by the sidewalls of the top and bottom members.
 11. An interlock for the top and bottom members of a foldably-constructed pallet comprising: a strap integral with the material comprising one or both of the top and bottom members of a foldably-constructed pallet, one or both of the top or bottom members being folded to form sidewalls when assembled to each other to form a pallet; a locking formation formed on the end of said strap; a knife cut in the material comprising the opposite bottom or top member for receiving the locking formation, said strap being folded over the sidewall and into contact with the opposite bottom or top member with the locking formation inserted into the knife cut at the corner of the pallet.
 12. The interlock of claim 11 wherein a portion of the material comprising the top or bottom members bears against the locking formation when the locking formation is inserted into the knife cut.
 13. The interlock of claim 11 additionally comprising means for retaining the locking formation in the knife cut.
 14. The interlock of claim 13 wherein said locking formation retaining means comprises a notch formed on the locking formation for bearing against the material comprising the top or bottom member when the locking formation is inserted into the knife cut therein.
 15. The interlock of claim 13 wherein said locking formation retaining means comprises a retaining tab formed when the locking formation is inserted into the knife cut therein.
 16. The interlock of claim 11 wherein both top and bottom members are provided with a respective locking strap, the locking strap integral with the top member being folded over the sidewall on one side of the corner of the pallet and the locking strap integral with the bottom member being folded over the sidewall of the other side of the corner of the pallet.
 17. A method of interlocking top and bottom substantially planar members in nested relation comprising the steps of: folding a flap formed on a substantially planar top member to a position substantially perpendicular to the planar surface of the top member; folding a flap formed on a substantially planar bottom member to a position substantially perpendicular to the planar surface of the bottom member, the flap on the top member forming a sidewall and the flap on the bottom member forming an end wall when the top and bottom members are in nested relation; folding a strap extending from either the flap forming the sidewall or the flap forming an end wall around the corner formed by the end wall and sidewall; inserting the end of the strap into a slot formed in the other of the sidewall or the end wall; and retaining the end of the strap in the slot.
 18. The method of claim 17 wherein the slot is provided with a knife cut extending therefrom, the strap being driven through the slot and knife cut by a mandrel that engages the strap.
 19. The method of claim 18 wherein the strap is retained in the slot by interaction of a tab formed on the end of the strap with the corners formed by the knife cut and the slot.
 20. The method of claim 18 additionally comprising deflecting the corners formed by the knife cut and the slot in the direction in which the strap is driven by the mandrel to facilitate insertion of the strap into the slot.
 21. Apparatus for assembling the top and bottom blanks of a foldably-constructed pallet in nested relation comprising: an intake for taking up and registering a top blank; an intake for taking up and registering a bottom blank; clamps for folding the registered top and bottom blanks to form support ribs therein; a joiner for compressing the folded top and bottom blanks to each other in nested relation to form the pallet; and a mandrel for folding a strap formed on either of the top or bottom blank into contact with the opposite blank and for inserting the end of the strap into a cut formed in the material comprising the opposite blank for interlocking the top and bottom blanks.
 22. The apparatus of claim 21 additionally comprising a programmable controller for regulating each of said top intake, said bottom intake, said clamps, said joiner, and said mandrel.
 23. The apparatus of claim 21 additionally comprising clamps for folding said top and bottom blanks to form sidewalls, the strap being folded into contact with the opposite blank at the corner formed by adjacent sidewalls. 